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Experimental study of crystallization kinetics in one-component system
Pivovarská, Lucie ; Špillar, Václav (advisor) ; Jeřábek, Petr (referee)
Crystallization is main internal process in magma chambers and it influences, among other things, the eruptive behavior of volcanoes, or formation of some types of ore deposits. Crystallization is a kinetically controlled process, which includes mainly nucleation and growth of crystals. Despite its importance, mechanisms and rates of crystallization are poorly constrained. In this work, a pilot set of fifteen kinetic crystallization experiments were performed in a one-component pure diopside system. The experiments were performed by melting and crystallization in an atmospheric furnace under various levels of undercoolings ranging from 41 to 450 řC below the temperature of liquidus. The experimental products allowed quantitative calculation of nucleation rates (18.7 mm-3 s-1 under the undercooling of 491 ř C) and qualitative estimate of crystal growth rates (maximum of 8.88 × 10-4 cms-1 at the undercooling of 240 řC). Observations of crystallization products further indicate that the crystal growth occurred on crystallographically defined faces with euhedral morphology over the entire range of undercoolings with absence of dendritic growth. In addition, heterogeneous nucleation was observed at high undercoolings, but cannot be excluded under a broader range of conditions. Experiments also exclude...
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